Odd... Were the threats phoned in from the planes, or from the ground? I'm betting the latter -- some jerk probably found a couple of closely-spaced flights into JFK on the "Flight Status" website, and thought it'd be fun to pull a prank.
both flights are Deltas one was out of India...hmmm
Two Delta flights .. threat phoned in warning of hijackers on board. Confirmation that both cockpits are secure and operations are "normal."
Delta flights 119 and 81.
Phone call came from Paris.